A flexible pipe is constituted by a hose or a plurality of interconnected hoses, with the or each hose being fitted at its end with connection endpieces.
In conventional manner, a hose comprises from the center towards the outside:
armoring that resists crushing, that is not leakproof, also referred to an inner carcass, which is typically constituted by helically winding an interlocking section member, e.g. a steel strip, and provided at each end with an endpiece that is also known as a stop ring; PA1 a polymer layer covering the inner carcass, penetrating into the gaps therein and providing an outer surface that is substantially cylindrical and uniform, the polymer layer also being referred to as a sacrificial sublayer; PA1 a sealing barrier constituted by a polymer layer extruded over the sacrificial sublayer, with the purpose of the sacrificial layer being to provide the sealing barrier with a base surface that is substantially uniform; PA1 reinforcement for withstanding mechanical forces, in particular from internal pressure and from traction, this armoring typically comprising crossed armoring sheets of helically wound steel wires; and PA1 a protective outer polymer sheath.
Optionally, the hose may also include, between the sealing barrier and the armoring sheets, a polymer layer referred to as an anti-creep layer that covers said sealing barrier and that serves to prevent it creeping into the gaps of the armoring sheets.
The hose must be fixed to each connection endpiece in such a manner as to ensure both continuity of the sealing of the flexible pipe, and as to ensure that traction forces due to the bottom effect are conveyed. These forces are taken up entirely by the armoring sheets in conventional manner and as described below.
It is known to provide sealing between the endpiece and the sealing barrier by means of a sealing gasket constituted by a metal bush having a substantially conical outer surface and threaded and crimped onto the sealing barrier. The metal bush also holds the sealing barrier axially in the connection endpiece, by opposing any residual axial stresses due to the method by which the hose is manufactured. The sealing barrier is clamped between the metal bush and the inner carcass, which carcass has sufficient mechanical strength to withstand crimping of the metal bush.
Unfortunately, that known technique does not provide entire satisfaction since it has been observed in some cases that sealing is lost due to a drop in the crimping exerted by the metal bush, and the Applicant attributes this to sweating out of plasticizing agents contained in the material constituting the sealing barrier.
An increase in the crimping ratio of the bush, where crimping ratio is defined as the ratio of the penetration depth of the metal bush over the combined thickness of the sealing barrier plus the sacrificial sublayer prior to crimping, does not make it possible in satisfactory manner to obtain long-lasting sealing since an excessive crimping ratio (greater than 60%) increases the risk of the sealing barrier tearing.